High performance automobiles use aerodynamic elements to generate downward force (or downforce) on the vehicle to increase contact with the road, and provide increased stability and control. Underbody diffusers are useful in generating such aerodynamic downforce. Such vehicle underbody diffusers use vertical strakes to create airflow channels. Smooth airflow through the channels speeds up as the area increases toward the rear of the vehicle generating downforce on the rear wheels, which are typically the driven wheels of such high performance vehicles.
The smoother the airflow through the channels, the greater the airflow speed through the channels and the greater the resulting downforce that is generated. Vertical strakes that are positioned closer to the road surface are better at limiting turbulent interaction between the channels. Limiting cross channel turbulent airflow is desirable because such cross channel turbulent airflow disrupts the smooth airflow in the channels, which slows airflow speed reducing the resulting downforce.
High performance automobiles are often driven in both public street environments and closed race track environments. For example, it is not uncommon for owners of high performance automobiles to drive these vehicles on public streets and to also periodically race them on closed race tracks. Of course, driving on public streets is not conducive to elements being positioned near public road surfaces, which are often relatively uneven and include relatively large dips and bumps.
Complicated systems have been developed to automatically or dynamically raise and lower underbody panels supporting vertical strakes in order to match driving conditions. Examples of such systems include U.S. Pat. No. 6,575,522, which issued to Borghi et al. on Jun. 10, 2003, and U.S. Pat. No. 8,731,781, which issued to Prentice on May 20, 2014, which are both incorporated herein by reference. Not only are such systems complex, but they are expensive to implement and maintain. In addition, because lowering the underbody panels increases the effective cross-sectional area of the vehicle, such lowering generates increased drag. Indeed, the perceived need to dynamically raise and lower the panels is due, at least in part, to a desire to properly balance downforce and drag under current driving conditions.